Twisting of textile yarns



April 17, 1962 F. SCRAGG El'AL TWISTING OF TEXTILE YARNS 5 Sheets-Sheet1 Filed Aug. 22, 1957 Inventors FEEDER/CK 5612466 ym/p paen/mao B v AAttorney;

April 17, 1962 F. SCRAGG ETAL 'TWISTING OF TEXTILE YARNS 5 Sheets-Sheet2 Filed Aug- 22, 1957 Inventors FIQE'DER/CK JCQAGG P/l/Z/P FORWARDAttorneys Apnl 17, 1962 F. SCRAGG ETAL 3,029,591

TWISTING 0F TEXTILE YARNS Filed Aug. 22, 1957 3 Sheets-Sheet 3 v Fig. 6.

Inventors FREDER/CK $621466 PH/Z/P FORM 4RD A ttomeys 3,029,591 TWISTINGF TEXTILE YARNS Frederick Scragg, Tytherington, Macclesfield, and PhilipForward, Maccleslield, England, assignors to Sydney 8:

E. Scragg Limited, Macclesfieid, England Filed Aug. 22, 1957, Ser. No.679,682 Claim priority, application Great Britain Aug. 23, 1956 8Claims. (Cl. 57-157) The present invention concerns the twisting oftextile yarns, and is more especially concerned with imparting so-calledfalse twist for purposes such as the production of crimped yarns fromyarns composed of endless synthetic filaments.

False twisting has hitherto been effected by passing a yarn over amember attached to a hollow spindle through which the yarn iscontinuously drawn during rotation thereof. Since this arrangementimparts one turn of false twist for each revolution of the spindle, therate of twisting is limited by the maximum spindle speed attainable inpractice.

An object of the present invention is to remove the above limitation andthereby to enable higher values of twist to be imparted to yarns movingat a given longitudinal speed than has been practicable heretofore.

According to the present invention, a longitudinally moving yarn istwisted by frictional engagement between it and a surface movingsubstantially at right angles to the yarn axis at the locus of contact.The yarn is thus rolled round about its ownaxis relative to thefrictional surface so that the amount of twist will depend directly uponthe linear relative speed and inversely upon the circumference of theyarn.

In order to ensure adequate frictional engagement, the yarn may be urgedby its own longitudinal tension into rolling contact with a movingfriction surface of convex arcuate profile, or it may be more positivelyengaged by the provision of a pressure surface urged towards thefriction surface with the yarn therebetween. Two friction surfacesmoving in opposite directions may be used and these may, if desired, bearranged so that each constitutes a pressure surface relative to theother.

The friction surface may be presented by a body of rotation, or by alongitudinally displaced flexible member such as a belt.

Preferably the friction surface is presented by a body of rotation atleast in part concave relative to its own rotary axis and the yarn isguided so as to tend to move in a fixed direction towards or away fromthe said axis. By such an arrangement the yarn tends to assume astabilised position at the nearest point on the surface to its directionof guiding. For this purpose two friction surfaces, convex in profileand partially concave relative to their axes, may be presented bymembers carried by hollow rotary spindles disposed side by side androtating in opposite ang ular directions whereby the yarn is led in oneaxial direction through one spindle and in the opposite axial directionthrough the other spindle.

As an alternative the friction surfaces of the two spindles may face oneanother, the spindle axes being offset to such an extent that the yarnmust pass through the first spindle and then be deflected in a radiallyoutward direction relative thereto to enter the second spindle in aradially inward direction and thereafter to pass through the secondspindle in a direction parallel to its direction of travel through thefirst spindle.

The invention will be described further by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a fragmentary vertical section showing a simple arrangementhaving a single friction surface;

3,029,591 Patented Apr. 17, 1962;

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FIG. 2 is a similar view of an arrangement including two frictionsurfaces;

FIG. 3 is a similar view showing another arrangement including twofriction surfaces;

FIG. 4 is a similar view showing a further arrangement including twofriction surfaces;

FIG. 5 is a horizontal section on the line V-V of FIG. 4;

FIG. 6 is a diagrammatic vertical section showing parts of a false twistunit incorporating an arrangement such as that of FIGS. 4 and 5;

FIG. 7 is a detail on an enlarged scale viewed from the right of FIG. 6;and

FIG. 8 is a diagrammatic vertical section of a machine comprisingcombined false twist and yarn modifying units incorporating anarrangement similar to that ,of FIGS. 4 and 5.

A rotary hollow spindle 15 (FIG. 1) carries upper and lower pigtailguides 16 and 17 respectively. The yarn 13 is drawn downwardly throughthe guides and through the lower part of the spindle 15 which it entersthrough an aperture below the guide 17.

A friction surface 10 of convex profile is presented by an annulus ofresilient material such as synthetic rubber fixed within a ring 18carried by a bracket 19.

On rotation of the spindle 15 the yarn, whilst moving downwardly isurged by its longitudinal tension into contact with the surface 10 overan arcuate locus. The rotary movement of the spindle and guide causesthe yarn to be translated around the surface 10 in a direction ofrelative movement substantially at right angles to the downwardlongitudinal movement of the yarn. This relative movement causes theyarn to be rolled about its own axis thereby imparting a high degree offalsetwist thereto. V

In a second embodiment (FIG. 2) the yarn-23 passes over a stationaryguide 25 and then passes between two contra-rotating annular frictionsurfaces 20 and 21 and after passing over another stationary guide 26travelsin a direction coaxial with the common axis of rotation of thesaid surfaces. The direction defined by the yarn 23 as it passes fromguide 25 to guide 26 is not quite radially of the axes of the surfaces20, 21 thus, the angle between the said axes and the yarn 23 is lessthan The surfaces are presented by resilient facings on the ends ofrotary members 27 and 28 respectively which are con: nected by gearingand a layshaft 29 to rotate at similar speeds in opposite directions.The members 27 and 28 are arranged so that the surfaces 28 and 21 arefixed in an axial direction for rotation with a relatively small spacetherebetween. The yarn 23, entering the opening between the surface 20,21, contacts the inner corner of the surface 20 and the outer corner ofthe surface 21 because of the less than perpendicular entry angle andbecause of the tension in the yarn 23. By this means, both frictionsurfaces 20, 21 are effective to twist the yarn as it passes through theopening therebetween.

A third embodiment (FIG. 3) includes a first friction surface 30presented by part of the external periphery of a resilient ring 35carried on a pulley 36, and a second friction surface-31 present by partof the internalperiphcry of a resilient facing carried on aninternalbead 37 supported by a spider from a generally cylindrical casing 38.The pulley 36 is mounted on a spindle 39 which is rotatably mounted inbearings in a cylindrical bracket portion 310 of a fixed bracket 311.The bracket portion 314? carries a larger diameter cylindrical portion312 upon which the casing 38 is rotatably mounted. The spindle 39 isconnected by bevel pinions to a layshaft 313 which 0 is rotatablymounted in the bracket 311 and which in 3 pivotally mounted on shaft 41which is secured to the bracket 311. By means of this gearing thespindle 39 and the casing 38 must rotate in opposite directions at thesame speed if either of them is driven and hence the surfaces 30 and 31are contra-rotatory. The yarn 13 is drawn downwardly through a fixedpigtail guide 314, in contact over an external arcuate locus on thesurface 30 and over an internal arcuate locus on the surface 31 andthence downwardly between the cylindrical bracket portions 310 and 312.

In a :fourth embodiment (FIGS. 4 and 5) .two friction surfaces arepresented by rubber members 45 and 46 which are concave in plan (Le.partially concave relative to their rotary axes) and of convex profilein vertical section. The member 45 is carried at the lower end of ahollow spindle in the form of a steel cylinder 47 provided with bronzebearing liners 48 and 49 secured as a press fit therein. Similarly themember 46 is carried by a hollow spindle in the form of a cylinder 410having liners 411 and 412 secured therein.

Two fixed steel cylindrical guides 413 and 414 are supported from afixed plate 415.

The lower end portions of these guides are flanged at 416 and 417respecitvely to engage the lower end faces of the liners 49 and 412respectively and thereby to retain the cylinders 47 and 410 in arotatably mounted position on the guides as shown.

The upper end portions of the cylinders 47 and 416 carry intermeshinggear wheels 4118 and 419 respectively so that when the cylinder 410 isrotated by frictional engagement with a belt 422 the cylinder 47 alsorevolves.

The guides 413 and 414 each have a vertically extending bore 420 and 421respectively through which the yarn 43 is guided.

In operation the yarn passes downwardly through the bore 421 and aroundthe surface which is concave in plan presented by the rubber member 46and radially outward therefrom to the surface presented by the member 45. The yarn passes radially inwards over the surface of the member 45and thereafter upwardly through the bore 420. It will be seen that anytendency for the yarn to wander circumferentially around either of themembers 45 or 46 is counteracted by their concave shape in plan therebycausing the yarn to follow the shortest path in the position defined bythe bores 420 and 421 in the guides 413 and 414 respectively.

Crimped yarn may be produced from a plain yarn composed of a pluralityof endless filaments, the yarn being false twisted in accordance withthe invention, the yarn also being heated immediately before coming intocontact with the friction surface, so that in the twisted condition ofthe yarn where it passes the friction surface its individual filamentsare substantially free of twist.

A false twist unit (FIGS. 6 and 7) in a simple form comprises a gatetensioner 75, a heater 76 below the gate tensioner, two frictionsurfaces 70 and 71 (of the kind as shown in FIG. 4) and an outward feedroll 77. It has been found however that the action of the gate tensioneris apt to be erratic due to the twist in the yarn 73 passing upwardsthrough the heater against the direction of movement of the yarn. Inaccordance with a further feature of the invention, however, twistblocking means is provided between the gate tensioner and the heater.Thus the twist may be blocked below the tensioner by passing the yarnaround two grooved rolls 78 and 79 preferably twice, each roll thenhaving two peripheral guide grooves.

The present invention, by considerably increasing the linear speed atwhich synthetic crimped yarns may be produced, ofliers the valuablepossibility of subsequently modifying the properties of the yarn in asingle continuous process.

Thus the plain yarn is passed from a supply bobbin 85 (FIG. 8) through agate tensioner 86, over a pair of twist blocking rolls 8 8, 89, over aheater 810, over frictional twisting surfaces 80, 81, and around guiderolls 811, 812. The thus formed crimped yarn may then be passed directlyinto a yarn modifying unit to impart any desired combination of bulk orstretch to the crimped yarn by modifying it under the action of heat andtension. Such yarn modifying unit comprises for example feed rolls 813,814, a heater 820, feed rolls 821, 822, a guide roll 823 and windingdrum 824.

We claim: a

1. A method of imparting false twist to a yarn comprising the steps ofpassing'said yarn over the external peripheral surface of a rotatabledisk and through a rotatable ring while tensingsaid yarn across saidexternal peripheral surface of said disk and across the internalperipheral surface of said disk for frictional engagement of said yarntherewith and rotating said disk and ring about their respective centralaxes to cause twisting of said yarn.

2. A method of imparting false twist to a yarn comprising the steps ofpassing said yarn through two coplanar rotatable rings while tensingsaid yarn across the internal peripheral surfaces of both of said ringsfor frictional engagement of said yarn therewith and rotating both ofsaid rings about their respective central axes to cause twisting of saidyarn.

3. A method for imparting a false twist to a moving yarn comprising thesteps of passing said yarn progressively through two coplanar circularrotatable devices having friction surfaces said yarn being in frictionalengagement with each of said surfaces and rotating said devices suchthat said surfaces move substantially transverse to said yarn andthereby roll and twist said yarn about its own axis.

4. In a method of false'twisting a yarn, the steps of continuouslyadvancing the yarn longitudinally; bending the yarn, as it advanceslongitudinaily, along a convex annular peripheral portion of a firstrotating member whose peripheral portions turns transversely withrespect to the longitudinally advancing yarn so as to twist the samewhile changing the longitudinal direction of advance thereof; thenbending the longitudinally advancing yarn, as it leaves said firstmember, along a convex annular peripheral portion of a second rotatingmember whose peripheral portion also turns transversely with respect tothe longitudinally advancing yarn and continues to twistthe same Whilefurther changing the longitudinal direction of advance thereof; and thencontinuing the longitudinal advance of the yarn beyond said secondmember.

5. In a method as recited in claim 4, said first and second rotatingmembers being coaxial and said peripheral portions of said members beingthe outer peripheral portion of one of said members and an innerperipheral portion of the other of said members so that the yarn movesalong a substantially S-shaped path while being twisted by said rotatingmembers.

6. in a method as recited in claim 4, said first and second rotatingmembers being located beside each other.

7. In a method as recited in claim 4, said first and second rotatingmembers being located beside each other and having substantiallyparallel axes of rotation, respectively.

8. In a method as recited in claim 4, said first and second rotatingmembers being located beside each other and said peripheral portionsthereof being at the inner peripheries of said rotating members so thatthe yarn is bent along substantially U-shaped path as it passes throughsaid rotating members. in engagement with said peripheral portionsthereof.

References Cited in the file of this patent UNITED STATES PATENTS (Gtherreferences on following page) 5 UNITED STATES PATENTS Stockly Aug. 2,1949 Abbott Sept. 12, 1950 Snider Sept. 26, 1950 Brown Mar. 25, 1952 5Brown Sept. 20, 1955 Vandamme et a1 Apr. 17, 1956

